[PATCH] scsi: libiscsi: use kvzalloc for iscsi_pool_init

Kyle Fortin
2017-05-17T20:21:54Z

iscsiadm session login can fail with the following error:

iscsiadm: Could not login to [iface: default, target: iqn.1986-03.com...
iscsiadm: initiator reported error (9 - internal error)

When /etc/iscsi/iscsid.conf sets node.session.cmds_max = 4096, it results
in 64K-sized kmallocs per session. A system under fragmented slab
pressure may not have any 64K objects available and fail iscsiadm session
login. Even though memory objects of a smaller size are available, the
large order allocation ends up failing.

The kernel prints a warning and does dump_stack, like below:

iscsid: page allocation failure: order:4, mode:0xc0d0
CPU: 0 PID: 2456 Comm: iscsid Not tainted 4.1.12-61.1.28.el6uek.x86_64 #2
Call Trace:
[<ffffffff816c6e40>] dump_stack+0x63/0x83
[<ffffffff8118e58a>] warn_alloc_failed+0xea/0x140
[<ffffffff81191df9>] __alloc_pages_slowpath+0x409/0x760
[<ffffffff81192401>] __alloc_pages_nodemask+0x2b1/0x2d0
[<ffffffffa048f6c0>] ? dev_attr_host_ipaddress+0x20/0xffffffffffffc722
[<ffffffff811dc38f>] alloc_pages_current+0xaf/0x170
[<ffffffff81192581>] alloc_kmem_pages+0x31/0xd0
[<ffffffffa048f600>] ? iscsi_transport_group+0x20/0xffffffffffffc7e2
[<ffffffff811ad738>] kmalloc_order+0x18/0x50
[<ffffffff811ad7a4>] kmalloc_order_trace+0x34/0xe0
[<ffffffff8146ee30>] ? transport_remove_classdev+0x70/0x70
[<ffffffff811e843d>] __kmalloc+0x27d/0x2a0
[<ffffffff810c8cbd>] ? complete_all+0x4d/0x60
[<ffffffffa04af299>] iscsi_pool_init+0x69/0x160 [libiscsi]
[<ffffffff81465d90>] ? device_initialize+0xb0/0xd0
[<ffffffffa04af510>] iscsi_session_setup+0x180/0x2f4 [libiscsi]
[<ffffffffa04c5a60>] ? iscsi_max_lun+0x20/0xfffffffffffffa9e [iscsi_tcp]
[<ffffffffa04c531f>] iscsi_sw_tcp_session_create+0xcf/0x150 [iscsi_tcp]
[<ffffffffa04c5a60>] ? iscsi_max_lun+0x20/0xfffffffffffffa9e [iscsi_tcp]
[<ffffffffa048a633>] iscsi_if_create_session+0x33/0xd0
[<ffffffffa04c5a60>] ? iscsi_max_lun+0x20/0xfffffffffffffa9e [iscsi_tcp]
[<ffffffffa048abd8>] iscsi_if_recv_msg+0x508/0x8c0 [scsi_transport_iscsi]
[<ffffffff811922eb>] ? __alloc_pages_nodemask+0x19b/0x2d0
[<ffffffff811e6d69>] ? __kmalloc_node_track_caller+0x209/0x2c0
[<ffffffffa048b00c>] iscsi_if_rx+0x7c/0x200 [scsi_transport_iscsi]
[<ffffffff81623dc6>] netlink_unicast+0x126/0x1c0
[<ffffffff8162468c>] netlink_sendmsg+0x36c/0x400
[<ffffffff815d2fed>] sock_sendmsg+0x4d/0x60
[<ffffffff815d596a>] ___sys_sendmsg+0x30a/0x330
[<ffffffff811bc72c>] ? handle_pte_fault+0x20c/0x230
[<ffffffff811bc90c>] ? __handle_mm_fault+0x1bc/0x330
[<ffffffff811bcb32>] ? handle_mm_fault+0xb2/0x1a0
[<ffffffff815d5b99>] __sys_sendmsg+0x49/0x90
[<ffffffff815d5bf9>] SyS_sendmsg+0x19/0x20
[<ffffffff816cbb2e>] system_call_fastpath+0x12/0x71

Use kvzalloc for iscsi_pool in iscsi_pool_init.

Signed-off-by: Kyle Fortin <kyle.fortin-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Kyle Fortin <kyle.fortin-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Reviewed-by: Joseph Slember <joe.slember-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Reviewed-by: Lance Hartmann <lance.hartmann-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
drivers/scsi/libiscsi.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index dd6828f..42381ad 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -2556,7 +2556,7 @@ int iscsi_eh_recover_target(struct scsi_cmnd *sc)
* the array. */
if (items)
num_arrays++;
- q->pool = kzalloc(num_arrays * max * sizeof(void*), GFP_KERNEL);
+ q->pool = kvzalloc(num_arrays * max * sizeof(void*), GFP_KERNEL);
if (q->pool == NULL)
return -ENOMEM;

@@ -2590,7 +2590,7 @@ void iscsi_pool_free(struct iscsi_pool *q)

for (i = 0; i < q->max; i++)
kfree(q->pool[i]);
- kfree(q->pool);
+ kvfree(q->pool);
}
EXPORT_SYMBOL_GPL(iscsi_pool_free);

--
1.7.1